The True Lightning Rune is one the 27 True Runes. It is associated with the element of lightning, and all lesser runes of similar elements (Lightning, Thunder) descend from it. The rune played a part in both Fire Bringer Wars in the Grasslands Territories, and both times it was wielded by Geddoe. After the end of the First Fire Bringer War, Geddoe continues to house the rune on his right hand, but he kept it hidden and unused, even from his own squad, so as to not draw attention from Harmonia or other potential enemies who would seek to take the rune from him. When the Second Fire Bringer War was beginning to envelope the Grasslands, Geddoe decided to reveal the True Lightning Rune and use it's powers once again. He joined the Fire Bringer Army and put his rune to great use against the invading Harmonian Forces.
During a mission to rescue the Le Beque villagers, The True Lightning Rune is stolen by Luc and Sarah by utilizing Luc's True Wind Rune and Sasarai's stolen True Earth Rune, who subsequently go on to steal the True Water and Fire Runes from Chris and Hugo respectively. The Army pursues Luc and his team to the Ceremonial Site. At the site, Geddoe battles Yuber, who was tasked with protecting the True Lightning Rune. Yuber is defeated and Geddoe is able to reclaim his rune.
- If Geddoe is selected as the wielder of the True Fire Rune in Suikoden III instead of Hugo, then Hugo will bear the True Lightning Rune instead.
- Soaring Bolt: Deals 900 damage divided among all foes.
- Furious Blow: Deals 1000 damage to target and line of sight foes beyond.
- Thunder Storm: Deals 1100 damage to all foes.
- Hammer of Raijin: Deals 1800 damage to target.
- This rune does the most direct damage to enemies out of any True Rune in the series.